1. Field of the Invention
The present invention relates to a radio communication system control method, a radio communication system, and an information processing apparatus used therein. More particularly, the invention is directed to a system and method wherein radio communications links a server and terminals via a plurality of base stations.
In a conventional radio or wireless LAN system, the radio terminal apparatus assumes that an appropriate link or connection exists between a base station and a server (parent machine and child machine), even in situations where there is no proper link between the base station and the server. Transmission of data, therefore, beginning based upon this erroneous presumption. Communication errors therefore occur; due to the fact that the radio terminal apparatus cannot recognize or identify the source of the communication error, the error is repeated.
2. Description of the Related Art
FIG. 8 shows a block diagram of one example of a radio LAN system in the prior art.
A communication system 100 in the prior art includes a server 101, radio terminal apparatus 102-1 through 102-N which communicate with the server through radio communication, and a communication apparatus 103. The communication apparatus 103 connects the server 101 with the radio terminal apparatuses 102-1 through 102-N through radio communication and forms radio LAN circuits.
The server 101 is connected with the radio terminal apparatuses 102-1 through 102-N via the communication apparatus 103, and performs predetermined processing in accordance with commands from the radio terminal apparatuses 102-1 through 102-N. The radio terminal apparatuses 102-1 through 102-N perform radio communication with the communication apparatus 103 and are connected with the server 101.
The communication apparatus 103 includes a plurality of base stations 104-1 through 104-M which perform radio communication with the radio terminal apparatuses 102-1 through 102-N, and a branching device (HUB) 105 which causes a communication circuit from the server 101 to branch to the plurality of base stations 104-1 through 104-M.
In the radio LAN system 100 in the prior art, for example, when the link of the base station 104-1 with the server 101 is disconnected for any reason as indicated by X in FIG. 8, the radio terminal apparatus 102-1 existing in the communication possible area of the base station 104-1 is completely independent and is not aware of the condition of link, the radio terminal apparatus 102-1 operates as if the link is normal and starts communication.
As a result, however, communication errors occur in radio terminal apparatus 102-1. However, radio terminal apparatus 102-1 does not recognize the cause of the communication errors; radio terminal apparatus 102-1 therefore continues the communication with base station 104, and the communication errors repetitively occur.
In the communication system discussed above, when the link between the server and a base station is disconnected, the radio terminal apparatus performs communication with the base station continuously even though the link between this base station and the server is disconnected. This occurs because the radio terminal apparatus is not aware of the condition of the link between the server and the base station. Communication errors therefore frequently and repetitively occur. Further, because the radio terminal apparatus cannot recognize the cause of the communication error, restoration cannot be performed easily.
When the number of base stations (parent machines) increases, there are additional problems; when malfunctions occur, for example, a great deal of labor and time are required for identifying and correcting the cause of the malfunction, and also restoring the errors caused by the malfunction.
The present invention has been developed in consideration of the above-mentioned problems. An object of the present invention is to provide a radio communication system control method, a radio communication system control method, a radio communication system, and an information processing apparatus used therein, wherein communication impossible conditions or communication breakdowns can be prevented from occurring in the radio communication system, therefore reducing communication errors.
The present invention is directed to a radio communication system in which a server and terminals communicate via a plurality of base stations, comprising a method which includes a link detecting step detecting conditions of links between the server and the plurality of base stations, and a communication stopping step stopping the communication between a base station and a terminal, disconnection of the link between the base station and the server having been determined as a result of detection in the link detecting step.
According to a first embodiment the present invention, as a result of the communication between the disconnected base station and the terminal being stopped in the stopping step, the terminal does not perform communication with the base station and thereby communication errors in the terminal can be avoided.
In a second embodiment of the invention, the communication stopping step stops the communication between the disconnected base station and the terminal by disconnecting a power supply in the base station through a command radio-transmitted from an adjacent base station.
According to this second embodiment, as a result of the disconnection of the power supply in the base station, through the command from the adjacent base station, the communication between the terminal and this base station is stopped.
In a third embodiment, the invention further comprises a communication switching step enabling communication between the server and the terminal through the base station adjacent to the disconnected base station, after the communication between the terminal and the disconnected base station is stopped.
According to the third embodiment, because the terminal which is intended to perform communication with the disconnected base station can perform communication with the adjacent base station, communication errors in the terminal can be avoided.
A fourth embodiment of the invention is one where the link detecting step repeatedly detects the links between the server and the plurality of base stations every predetermined time period. According to this embodiment, as a result of detection of the links between the server and the plurality of base stations every predetermined time period, any disconnection or failed link can be detected very quickly, communication from the terminal can be stopped, and communication error in the terminal can be avoided.
In a fifth embodiment, in a radio communication system according to the invention comprises a system including link detecting means for detecting conditions of links between the server and the plurality of base stations, and first communication stopping means, provided in the server, for stopping communication between a base station and a terminal, disconnection of the link between the base station and the server having been determined as a result of detection by the link detecting means. The stopping of the communication is performed by an adjacent base station.
According to this embodiment, the link detecting means detects the disconnected base station, and the communication stopping means stops the communication between the terminal and this disconnected base station. Because the terminal does not perform communication with the disconnected base station, communication errors in the terminal can be avoided.
According to a sixth embodiment, the server has a link condition management table for managing the conditions of the links between the server and the plurality of base stations. As a result of management of the conditions of the links of the plurality of base stations through the link condition management table, the overall condition of the system can be reliably determined, and the reliability of the system can be improved.
In a seventh embodiment, the communication stopping means provides a command for disconnecting the power supply in the disconnected base station. As a result, the power supply in the base station is disconnected through the other base station, and the communication between the terminal and the base station can be stopped.
In yet another embodiment of the invention, an eighth embodiment, the plurality of base stations have second communication stopping means for stopping the communication with the terminals when receiving the command. As a result of the plurality of base stations having the second communication stopping means for stopping the communication with the terminal when receiving the command, the communication between the terminal and the base station can be stopped in accordance with the command from the other base station.
A ninth embodiment of the invention is one where the second communication stopping means of the eighth embodiment has a power supply controlling means for disconnecting a power supply for driving the base station when receiving the command from another base station. As a result, the power supply in the disconnected base station is disconnected in accordance with the command from the other base station, and the disconnected base station becomes inoperable. The communication between the disconnected base station and the terminal can be stopped.
In a tenth embodiment, the link detecting means detects the conditions of the links between the server and the plurality of base stations every predetermined time period. As a result, the disconnected base station can be immediately detected, communication can be stopped, and communication errors can be avoided.
An eleventh embodiment of the invention is one where an information processing apparatus is connected with a plurality of radio communication stations, and comprises connection condition detecting means for detecting conditions of connections with the radio communication station, and command sending means for sending a command for stopping operation of a first radio communication station of the plurality of radio communication stations, to a second radio communication station of the plurality of radio communication stations, when it is detected that the first radio communication station is not connected with the information processing apparatus as a result of detection performed by the connection condition detecting means. As a result, it is possible to stop the operation of the first radio communication station through the command. Communication from the terminal to the first radio communication station can therefore be stopped, and communication errors in the terminal can be avoided.
In a twelfth embodiment, an information processing apparatus is connected with a higher-rank or higher priority apparatus, and performs processing in accordance with a command from the higher-rank apparatus, and also performs radio communication with a device. The embodiment includes command receiving means for receiving a command for the device provided by the higher-rank apparatus, the command instructing disconnection of a power supply of a disconnected or malfunctioning apparatus. Power supply disconnection apparatus recognizing means are provided for recognizing, based on the command, the particular apparatus in which the power supply is to be disconnected.
The information processing apparatus provides a command to the device, instructing disconnection of the power supply, the power supply being to be disconnected in the other apparatus and the other apparatus having been recognized by the power supply disconnection apparatus recognizing means.
By receiving the disconnecting command provided by the higher-rank apparatus, the power supply in the malfunctioning apparatus is disconnected and the communication between the malfunctioning apparatus and the terminal can be stopped.